Electrochemical cells for use in automatic dishwashing appliances are designed to operate by making use of the water electrolysis process wherein, at the anode-water interface, OH− being present in water due to electrolytic dissociation of water molecules donates an electron to the anode and can be thereby oxidized to oxygen gas which can be removed from the system. As a result, the H+ concentration can be enhanced at the anode-water interface so that H+ enriched acidic water can be produced. In a similar manner, at the cathode-water interface, H+ accepts an electron from the cathode and can be reduced to hydrogen to form hydrogen gas which can be similarly eliminated from the system so that the OH− concentration can be increased at the cathode-water interface whereby OH− enriched alkaline water can be generated. Further, when a halogen-containing water (such as, natural water containing sodium chloride or an aqueous solution of sodium chloride) can be subjected to electrolysis, halogenated mixed oxidants are generated in the electrolyzed water.
The following references disclose use of electrochemical cells: U.S. Pat. No. 5,932,171; U.S. Pat. No. 4,481,086; U.S. Pat. No. 4,434,629; U.S. Pat. No. 4,493,760; U.S. Pat. No. 4,402,197; U.S. Pat. No. 5,250,160; U.S. Pat. No. 5,534,120; U.S. Pat. No. 5,865,966; U.S. Pat. No. 5,947,135; JP Application No. 10057297A; JP Application No. 10179489A; JP Application No. 10033448A; JP Patent No. 09122060; JP Patent No. 2000116587; JP Patent No. 10178491; and EP Application No. 0983806A1.
The following references are also related to electrolyzed water: U.S. Pat. No. 3,616,355; U.S. Pat. No. 4,048,047; U.S. Pat. No. 4,062,754; U.S. Pat. No. 4,100,052; U.S. Pat. No. 4,328,084; U.S. Pat. No. 4,761,208; U.S. Pat. No. 5,314,589; U.S. Pat. No. 5,395,492; U.S. Pat. No. 5,439,576; U.S. Pat. No. 5,954,939 (equiv. EP 711,730); and WO 00/34184.
A problem associated with using an automatic dishwashing appliance containing an electrochemical cell and/or electrolytic device (hereinafter “cell and/or device”) to produce electrolyzed water for cleaning tableware in the absence of a specific ADD composition can be that there can be a potential for serious consumer dissatisfaction with the performance results. While use of electrolyzed waster alone provides a source of alkalinity and bleaching agent, it nonetheless lacks the ability to control hardness, dispersancy and/or corrosion, and therefore can result in unsatisfactory performance. Though some of the references disclose the use of detergent ingredients in conjunction with electrolyzed water, they are either not related to treating tableware in automatic dishwashing applications and/or do not provide for the control of hardness, dispersancy and/or corrosion required by the present invention.
U.S. Pat. No. 5,932,171 discloses a phosphate can be used in conjunction with electrolyzed water for sterilizing medical instruments in an immersive-type sterilization bath, but does not disclose or suggest the use of phosphate in an ADD composition in conjunction with electrolyzed water to control hardness, dispersancy and/or corrosion. Furthermore, this reference broadly discloses the use of electrolyzed water in conjunction with an “anticorrosive,” but fails to disclose specific anticorrosives (such as silicates, which are some of the most well known anticorrosives) or other “buffer additives.”
Similarly, U.S. Pat. No. 5,250,160 discloses a phosphate can be used in conjunction with electrolyzed water for sterilizing objects in an immersive-type sterilization bath, but does not disclose or suggest the use of phosphate in an ADD composition for building and/or cleaning purposes, or to control hardness, dispersancy and/or corrosion. Although this reference generally describes the use of electrolyzed water in conjunction with simple phosphates, the function of the phosphate disclosed by the reference can be simply to provide electrolytes to aid in the process of electrolysis.
JP Application No. 10179489A describes the use of detergent in conjunction with electrolyzed water but specifically teaches that the best mode reduces or abolishes the need for a detergent. U.S. Pat. No. 4,402,197 states the use of a detergent that “has a simplified formulation” but provides no details other than it could include an enzyme system. Similarly, the following references do not disclose electrolyzed water in conjunction with an ADD composition to control hardness, dispersancy and/or corrosion. JP Application No. 10057297A describes the use of a detergent but gives no specifics. JP Application No. 10033448A also broadly describes the use of “a detergent” and “an alkaline detergent” but provides no specifics. None of the abovementioned references disclose the benefits of hardness, dispersancy and/or corrosion control when treating tableware with electrolyzed water in conjunction with a specific ADD composition, as disclosed in the present application.
There remains a need to provide a specific ADD composition and a method of using a specific ADD composition in conjunction with electrolyzed water for treating tableware in an automatic dishwashing appliance for controlling hardness, corrosion and dispersancy in order to improve cleaning, sanitizing and stain removal performance.
It has now been surprisingly discovered that using electrolyzed water in conjunction with an ADD composition comprising a halogenated salt and a builder, such as phosphate and/or silicate, completes the portfolio of cleaning chemistry that can be necessary for a robust and satisfactory automatic dishwashing end result. The present invention meets this need by providing a unique halogenated mixed oxidant cleaning system. According to this invention, superior tableware cleaning, sanitizing and stain removal can be achieved when alkalinity for bleaching/sanitization can be provided by electrolyzed water, hardness control can be provided by phosphate and anticorrosion benefits are provided by silicates.
Electrolyzed water when combined with a builder, such as a phosphate and/or silicate, in the presence of a halogenated salt, can be particularly effective in removing a wide range of soils, microorganisms, and/or stains from soiled tableware. This combination will also allow ADD compositions to be sold without bleach, a distinct advantage over the prior art, while at the same time providing the cleaning performance of a powdered automatic dishwashing detergent composition that contains both enzyme and bleach. As a result, non-bleach-containing, enzyme-based liquid-gel automatic dishwashing detergent compositions could become a consumer-preferred ADD composition.